The detection and identification of sites of bacterial infection, for example in a post-operative patient, has long been problematic. Thus the methods currently available for such diagnosis, such as scintigraphic scanning using radionuclides (e.g. Tc-99m and Ga-67) and radiolabelled Antibodies, are not specific in that they do not provide a means of distinguishing between infection foci and centres of inflammation. A specific method is available involving the In-111 oxime labelling of removed and purified white blood cells which are then reintroduced to the patient. Such a method is time-consuming and requires skilled manipulation in order to obtain a satisfactory result. It is important to differentiate between the two conditions, because there is bacterial involvement in infection, whereas inflammation, while sometimes following on from infection, is often attributable to mechanical damage. Thus the follow-up treatment differs for infection and inflammation and may be critical.